Clutch not disengaging

[leewiffen]

Just started my 912 after the winter
Trying to engage gear it is grinding, making me think the clutch is not disengaging when I dip the clutch
Am I right in thinking this is a common issue?.....and if so is there an easy fix?
Ta
Lee

[barryb]

Hi

Plate is stuck to the flywheel. Get the engine warmed up then with a clear path put the car in second or third and spin the starter keeping you foot depressing the clutch. It will buck a bit but should free the plate.

good luck

Barry

[Barry]

If it is a stuck friction plate, just leave the car idling until fully hot, then (whilst running) just hold the clutch pedal down for, say, a minute at a time.

Often just the differential expansion and vibration of componants will be enough to free it. It's an old agricultural engineer's trick. I've used it a few times and it's worked each time for me, albeit on British iron. At the very least, it'll probably help it on the way to freeing off.

Lovely thing is it's dead easy and doesn't stress anything. If it doesn't work, you've lost nothing.

[Barry]

If you're feeling a bit braver, and confident of you ability to use jacks / axle stands, try the above. If that doesn't work, jack-n-stand the rear trailing arms so the wheels are just off the deck.

Stick it in third gear and fire it back up. Use the hand throttle to give moderate revs, and whilst keeping clutch dipped, dab the brakes, or indeed use foot throttle, clutch and handbrake.

This method allows you to gently load the clutch progressively without risking damage. Again, it's important to carry out procedue above, as it's that heat / vibration that's doing the main work for you.

I once freed off a TR4 clutch that appeared stuck solid (had been in leaky corrugated steel shed for a decade), using these methods. Took about forty minutes in total, by far and away the longest bit was letting it all warm up.

Essentially it's what (other) Barry says, heat then load .

[Kneeslider]

I put a new 200mm clutch into my 356 recently. All went well till I tried to get the clutch to disengage after it was all back together. Since the parts were all new; flywheel, driven plate and pressure plate, and all from the same manufacturer (QSC) I thought that they would all play together nicely. I also bought an OE clutch release bearing. I only wanted to put a new clutch in because I had the engine out to solve the distributor drive issues, and the teeth on the flywheel were very worn, and while you are at it etc. etc.

So began a load of faffing trying to work out what was wrong with my clutch. First of all, I tried adjusting by setting up the freeplay at the pedal, but still the clutch was clamped together, then I pulled the engine, and removed the cover plate and driven plate for a looksee. It all looked fine. There was a very small quantity of rust like staining on the flywheel, which must have been due to the engine having sat over winter in the garage, but not enough to make things stick. Hmmm. I had carefully cleaned all the grease off the new flywheel, and the cover plate surfaces several months ago, when it had first gone together. I started to try to measure things, reasoning that I had a worn out 180mm clutch and flywheel, so I should really try to find out why my new one was different.

The driven plate thickness was OK, and the flywheel measured up OK. When I put it in the first time I noticed that the part of the flywheel where the seal runs was rather rough, where it had been turned to size. Unfortunately the flywheel was too big to fit in my lathe, so I took it to a local engineering company who polished it for me. I was still at a loss to work out why my clutch wouldn't work, so called Calder Clutch Company Ltd. in Brighouse, who told me to take it to them and they would have a look.

After they put it on their test jig, it turns out that the driven plate was being clamped too firmly when the pressure plate was bolted up, and the diaphragm spring had gone through all its travel before the release bearing pressed on it. They spaced out the cover plate bolts with shims till the clutch could release properly. It turned out to need 90thou of shims before it worked properly. Their solution was to take 90thou of the surface of the pressure plate. To top it off, they only charged me £20! After seeing their clutch recon process, I am convinced that I will never buy a new clutch from anywhere else.

So, finally today for the first time I managed to drive the thing briefly on the driveway, so success is mine, eventually. Taken months to get through this voyage of discovery though.

So, beware of QSC clutches from the USA. They look the business, are balanced up OK, and seem quite nicely engineered (excepting having to polish the seal surface on the flywheel) I contacted the supplier and told him of my problems and he said that they would look into it, and offered his apologies, and suggested that I must have been supplied with the wrong cover plate or flywheel.